#!/usr/bin/python3
# ******************************************************************************
# Copyright (c) Huawei Technologies Co., Ltd. 2021-2021. All rights reserved.
# licensed under the Mulan PSL v2.
# You can use this software according to the terms and conditions of the Mulan PSL v2.
# You may obtain a copy of Mulan PSL v2 at:
#     http://license.coscl.org.cn/MulanPSL2
# THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT, MERCHANTABILITY OR FIT FOR A PARTICULAR
# PURPOSE.
# See the Mulan PSL v2 for more details.
# ******************************************************************************/
class SingleInstance:
    def __init__(self, cls):
        self._cls = cls
        self._instance_dict = dict()

    def __call__(self):
        if self._cls not in self._instance_dict:
            self._instance_dict[self._cls] = self._cls()

        return self._instance_dict[self._cls]